Cavitation-deterring energy-efficient fluid pump system and method of operation

ABSTRACT

A variable nozzle area jet pump is provided having a nozzle-sealing member resiliently urged to form a sealing closure. The sealing member is part of a normally non-passing pressure control valve that recirculates excess fluid back to the inlet of a positive displacement fluid pump. The fluid is recirculated with elevated pressure after a threshold fluid pressure is exceeded. The disclosed system provides for energy conservation and pump cavitation speed increase. The system may be integrated with an engine balance shaft module so as to provide low cost robustness to low speed gear noise emissions by application of the oil pump&#39;s drive torque to at lease one gearset.

CROSS REFERENCE TO RELATED APPLICATION

This application claims benefit of U.S. Provisional Application Ser. No.60/927,484 filed May 3, 2007, and entitled “Energy Efficient Fluid PumpSystem.” which is incorporated by reference herein in its entirety.

FIELD OF ART

The present invention relates generally to a fluid pump system for anengine or other system, and more particularly, to the provision of lowcost increases in the cavitation speeds of positive displacement fluidpumps, concurrent with useful power consumption reductions over a widerange of operational speeds, in applications offering limited packagingspace.

BACKGROUND

The use of an adjustable nozzle area jet pump having normallynon-passing pressure control valve functionality to conserve energy bydelivering pressurized recirculation flow back to the inlet of apositive displacement fluid pump under widely varying load conditions isknown in the art. The use of a positive displacement pump to reduce thetiming gear noise emissions of an engine balance shaft module at lowcost by applying the oil pump's driving torque to minimize gear toothseparation is also known. These types of engine balance shaft moduleapplications typically drive the pump at twice engine speed by means ofa driving connection with a twice engine speed balance shaft. Thisarrangement is beneficial in terms of both pump volumetric efficiency atlow speeds and required pump packaging space claim. However, suchapplications often represent significant challenge when an operatingspeed range that is often greater than an order of magnitude in breadthis combined with a requirement for copious low speed flow volume. Thisis due to increased-displacement pumps generally suffering from reducedcavitation speeds, those where pump filling becomes challenged for lackof sufficient inlet passage pressure. This challenging combination isbecoming increasingly commonplace with marketplace demands forever-improving engine performance. These demands result in engineapplications having both oil flow resistance-lowering features such asvariable valve timing, and increased peak operating speeds.

Jet pump recirculation of unused flow volumes has proven to be aneffective means of both reducing power consumption and increasing pumpcavitation speeds in case of high speed applications utilizing positivedisplacement pumps. The energy efficiency benefits of jet pumprecirculation are extendable into the lower portions of an operatingspeed range by means of the efficiency-broadening character ofadjustable nozzle jet pumps. Additionally, the elimination of theupstream-of-jet pump pressure drop of a separate flow control valve, byintegrating normally non-passing pressure control valve functionalityinto an adjustable nozzle jet pump offers the potential of improvedrecycling efficiency. However, current art systems typically require adifferential control valve means, responsive to the difference betweenthe inlet pressure and the discharge pressure of the positivedisplacement pump. This arrangement is much more costly andspace-consumptive than necessary to achieve the desired functionality ofoptimized energy efficiencies and cavitation speeds in fluid pumpsystems that for avoidance of cost, complexity, or packaging space claimrequire positive displacement pumps to function over a wide range ofspeeds. Other prior art adjustable nozzle jet pumps having normallynon-passing pressure control valve functionality similarly define muchmore costly and complex structures than are necessary for the purpose ofachieving the above-cited desired functionality.

Accordingly, while existing pump systems are adequate for their intendedpurposes, there exists a need for a simpler, lower cost, and less spaceclaim-consumptive fluid pump system for improving both cavitation speedand normal speed range power consumption. There is further need forthese improvements in applications where in order to minimize cost,complexity, and/or packaging spaceclaim, positive displacement pumps arerequired to function over a wide range of speeds.

SUMMARY OF THE INVENTION

A pump system is provided having a positive displacement pump. Thepositive displacement pump includes an inlet passage and a dischargepassage. The pump system further includes an adjustable nozzle jet pumpvalve. The adjustable nozzle jet pump valve includes a supply chamberfluidly coupled to the first positive displacement pump dischargepassage. The supply chamber includes a port with a seat surface. Amovable valve member having a sealing surface and a body portion isarranged in the adjustable nozzle jet. The sealing surface is arrangedin sealing contact with the seat surface when in a first position. Thebody portion has a first face sealingly positioned within the supplychamber, and an opposing second face. The first face has a first surfacearea. The adjustable nozzle jet pump valve further includes an urgingmember, a suction chamber and a throat passage. The urging member isarranged and coupled to the second face. The suction chamber is fluidlycoupled to the port. The throat passage fluidly is coupled to thesuction chamber and the inlet passage. The port, the suction chamber andthe throat passage are arranged in a continuous serial fluid connectionto the inlet passage.

Another embodiment pump system for a variable consumptive load is alsoprovided. The pump system includes a first positive displacement pumphaving an inlet passage and a discharge passage, wherein the dischargepassage is arranged to couple with the variable consumptive load. A jetpump valve is provided having a variable nozzle opening area directlyfluidly coupled between the discharge passage and the inlet passage. Thejet pump valve also includes means for changing the area of the variablenozzle opening in direct response to changes in a fluid pressure such asthat in the discharge passage. The jet pump valve further includes anurging member arranged to bias a member to close the variable nozzleopening. The jet pump valve further also includes a suction chamberadjacent the variable nozzle opening and arranged to receive fluid fromthe variable nozzle opening and from a fluid reservoir. A throat passageis provided in the jet pump valve and is coupled to the suction chamber.The throat passage is further fluidly coupled to receive fluid from thereservoir and from the variable valve opening. The throat passagetransfers the received fluid to the inlet passage.

A method of operating a pump system is also provided. The methodincludes pressurizing a fluid with a positive displacement pump. Thefluid is discharged into a discharge passage and a portion of the fluidis flowed from the discharge passage into a valve supply chamber.Pressure is applied to a valve body face. The valve body is moved toopen a port in the valve supply chamber. Fluid is ejected into a suctionchamber. Finally, the fluid pressure is increased at an inlet to thedisplacement pump by injecting the fluid across a suction chamber andinto a throat passage. The throat passage further receives fluid from areservoir by means of the suction chamber.

An internal combustion engine having a balance shaft assembly is alsoprovided. A first positive displacement pump having an inlet and adischarge passage is arranged such that the discharge passage is fluidlycoupled with the balance shaft assembly. A jet pump valve having avariable nozzle opening area is provided where the variable nozzleopening is fluidly coupled between the discharge and the inlet passage.The jet pump valve includes means for changing the area of the variablenozzle opening in direct response to changes in fluid pressure in thedischarge passage. The jet pump valve further includes an urging memberarranged to bias a member to close the variable nozzle opening. Asuction chamber is arranged in the jet pump valve adjacent the variablenozzle opening to receive fluid from the variable nozzle opening and afluid reservoir. The jet pump valve further includes a throat passagecoupled to the suction chamber. The throat passage is fluidly coupled toreceive fluid from the reservoir and the variable valve opening andtransfer the received fluid to the inlet passage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an exemplary embodimentcavitation-deterring energy-efficient pump system;

FIG. 2 is a schematic illustration of the pump system of FIG. 1 with thenozzle sealing member having been moved, by system pressure, for jetpump pressurization of the positive displacement pump's inlet;

FIG. 3 is a schematic illustration of the pump system of FIG. 1 havingan alternate embodiment supplemental pump that adds its flow volume tothat of the energy efficient pumping system to circumvent a “throatrestriction at pre-boost operating conditions” issue;

FIG. 4 is a schematic illustration of the pump system of FIG. 3 with thenozzle sealing member at a “bypass threshold” position;

FIG. 5 is a schematic illustration of the pump system of FIG. 3 with the“full bypass” nozzle sealing member position;

FIG. 6 is a schematic illustration of the pump system of FIG. 1 with analternate embodiment arrangement of circumventing the “throatrestriction at pre-boost operating conditions” issue;

FIG. 7 is a schematic illustration of the pump system of FIG. 6 at asystem pressure that has moved the nozzle sealing member and initiatedboost pressure, or reduction in vacuum magnitude, in the throat-to-pumpinlet passage or diffuser, wherein the check valve ball is shown seated;

FIG. 8 is a schematic illustration of the pump system of FIG. 1 havingan alternate embodiment, a low cost, low mass, and vibration-robustcheck valve in the throat-bypassing supply passage;

FIG. 9 is a schematic illustration of the pump system of FIG. 1 withanother alternate embodiment check valve arrangement, a so-called reedvalve assembly check valve in the throat-bypassing supply passage;

FIG. 10 is a schematic illustration of the pump system of FIG. 1 with analternate embodiment wherein a nozzle supply cavity sealing partitionisolates the sealingly mobile pressure area of the nozzle sealing memberfor control of system pressure at a location downstream of a flowresistance, by means of a separate remote pilot pressure controlpassage;

FIG. 11 is a schematic illustration of the pump system of FIG. 10 havinga positive seal between the nozzle sealing member and the nozzle supplycavity sealing partition;

FIG. 12 is a schematic illustration of the pump system having analternate embodiment electronic actuator as a control device wherebysystem delivery pressure may be electronically controlled in response toa signal;

FIG. 13 is a schematic illustration of a pump system with a combinationof remote pilot and electronic pressure controls, whereby systempressure is passively managed to maintain thresholddownstream-of-resistance pressure targets, and may additionally beactively managed;

FIG. 14 is a schematic illustration of the pump system providing fordirect movement of the nozzle sealing member by an electronic pressurecontrol;

FIG. 15 illustrates the pump system of FIG. 1 with a leakage-proofnozzle sealing member;

FIG. 16 illustrates another alternate embodiment pump system having analternate embodiment leakage-proof nozzle sealing member;

FIG. 17 illustrates a graphical comparison between the empiricalpressure curves of a conventional positive displacement pump system andthe exemplary embodiment, for the satisfaction of a hypothetical highspeed pressure target with the same positive displacement pump;

FIG. 18 illustrates a graphical comparison between the drive systempower consumptions of the conventional positive displacement pump systemand the exemplary embodiment, including a percentage difference curve;and,

FIG. 19 illustrates a schematic illustration of the pump system of FIG.1 coupled to a modular balance shaft assembly and internal combustionengine.

DETAILED DESCRIPTION OF THE INVENTION

Adjustable nozzle jet pumps are known for substantially extendedefficiency range in comparison with fixed nozzle area jet pumps. In theexemplary embodiment, a consistently high velocity of nozzle exit flowenables an automatically-adjusted variable nozzle area jet pump toprovide this performance advantage more or less continually in the caseof variable operating conditions. Substantial further efficiency rangeadvantages are gained over fixed area ratio jet pump-assisted positivedisplacement pumping systems by means of the exemplary embodiment's lowcost, compact integration of normally non-passing pressure control valvefunctionality with an adjustable nozzle-type jet pump.

The exemplary embodiment utilizes this simple normally non-passingpressure-controlling adjustable nozzle jet pump valve (hereafterreferred to as a “Jet Pump Valve” or “JPV”) to captively recirculateunused flow volumes back to a positive displacement pump's inlet withpressure boost (or reduction of vacuum) when the operating systempressure exceeds a predetermined threshold. The integration provided inthe exemplary embodiment effectively eliminates all of the flow energylosses customarily incurred with a so-called “bypass valve,” or“pressure-relief valve,” hereafter called a “PRV,” upstream of thenozzle supply passage. The JPV's “pressure relief” restriction itself isused as the means for efficiently propelling the unused flow volumes tohigh velocity in a useful direction. This elimination of a separate PRVthus increases the energy available to accelerate nozzle flow to highvelocities and thereby enables peak efficiency to be achieved at reducedcost in comparison with current art systems.

The elimination of a separate PRV provides, by means of the consistentlyhigh energy of nozzle discharge flow, the energy-saving benefit ofpressure enhancement to the inlet passage of the positive displacementpump to commence immediately upon the achievement of the predeterminedthreshold pressure and the associated onset of nozzle discharge flow.This greatly extends the range of operating conditions wherein usefulefficiency advantages are provided, in comparison with fixed nozzle jetpump recirculation systems.

Referring now to FIG. 1, the exemplary embodiment cavitation-deterringenergy-efficient fluid pump system 10 is illustrated. The arrowsillustrated in the Figures represent the direction of flow of fluid toand from system 10, etc. The system 10 includes a pressure-controllednozzle sealing member 30 which is continuously moveable between a firstclosed position and a second fully open position. As used herein, theterms “closed” and “open” refer to the extent of sealing. The nozzlesealing member includes an axisymmetric tapered seat region 34 of thenozzle sealing member 30 which contacts an axisymmetric seat region 38adjacent the radially inner and preferably longitudinal extremity of thejet pump nozzle. The seat region 38 is formed in a first end of a nozzlesupply chamber 32. The nozzle sealing member's 30 travel away from thefirst position towards the second position is resisted by a resilienturging member 44, and motivated by fluid pressure acting upon at leastone reaction face 42. An annular area of the nozzle sealing member 30'sseat region 34 has a diameter greater than that of the nozzle seat 38.

During operation, a predetermined threshold of fluid pressure isrequired to overcome a predetermined force exerted by the resilienturging member 44 to open the nozzle. This provides control over thepressure of the discharge-to-load portion of the present fluid pumpsystem 10. In the exemplary embodiment, the resilient urging member 44is a compression spring. The nozzle sealing member includes a sealingmobility portion 36 comprising a valve body portion 40 adjacent to thespring 44 and opposite the seat region 34. The spring side of the body40 may include a captured volume, 46 within the body 40. In theexemplary embodiment, the spring 44 is positioned within the volume 46and a chamber 50. The volume 46 and chamber 50 are collectively referredto herein as a “spring pocket” or damping chamber 54.

In the exemplary embodiment, the chamber 54 is vented to atmosphericpressure through one or more damping orifice(s) 48 that are positionedso as to allow escape of air. In one embodiment the damping orifice 48is in communication with a damping orifice oil reservoir 52 (FIGS.10-14) having volume greater than the displacement of the nozzle sealingmember's 30 travel. Any rapid movement of the nozzle sealing member 30is thus resisted by oil viscosity in the damping orifice 48 after thespring pocket 54 has been substantially purged of air and the dampingorifice reservoir filled by oil. The resulting motion damping of nozzlesealing member 30 serves to smooth system pressure vis-à-vis positivepump inherent displacement “ripple” and the tendency for structuresinvolving springs and masses to exhibit resonance. The venting toatmosphere enables the system pressure to be controlled by the forcefrom urging member 44. Flow resistance characteristics of the dampingorifice 48 may be such that any leakage flow from the nozzle supplychamber 32 to the spring pocket 54 is discharged to the reservoirwithout pressure buildup in the spring pocket 54. The nozzle sealingmember 30 motion is allowed to be sufficiently rapid, such as under coldstartup conditions for example, to avoid excessively high transientsystem pressure.

In the exemplary embodiment, the member body portion 40 and the chamber50 are cylindrical in shape. The body portion 40 and chamber 50 thusform a piston and cylinder arrangement. It should be appreciated,however, that the shape of the body portion 40 and the correspondingchamber 50 may be altered, or alternative means of sealing mobility withrespect to the nozzle supply chamber may be provided, without deviatingfrom the scope of the claimed invention.

The nozzle sealing member 30 is sealingly mobile with respect to thesecond end of the nozzle supply chamber 32, and positioned opposite thenozzle seat 38. This allows the fluid pressure to act on the nozzlesealing member 30. When the fluid pressure within the nozzle supplychamber 32 is below a first threshold, the sealing member seat region 34is in contact with the nozzle seat 38. By maintaining the seal at lowspeeds, the desired fluid pressure is maintained in the dischargepassage 72 of a positive displacement pump fluid 70, such as an internaltip sealing rotor pump, commonly known as a gerotor pump. In oneembodiment, this sealing mobility may be provided by the aforementionedpiston and cylinder arrangement, but for embodiments where sealing mustbe complete, or at least relatively leak-free, alternative means ofsealing mobility, such as a diaphragm or bellows-type diaphragmapparatus for example, may be used. Nozzle sealing member 30 position,and thus system pressure, automatically adjusts in response torecirculation flow rate and viscosity of fluid from the dischargepassage 72 after exceeding the predetermined threshold of fluidpressure. The nozzle sealing member 30 is therefore independent of inletpressure, or lack thereof, with an advantageous reduction in complexity,size, and cost.

JPV nozzle discharge flow, when present as illustrated by the partiallyopened JPV of FIG. 2, is directed at consistently high velocity by theaxisymmetrically variable opening area between the nozzle sealing member30 and the nozzle seat 38, across an annular gap or suction chamber 56between the nozzle and a jet pump throat passage 60 having adjacentthroat inlet transition region 62. The throat passage 60 is also beingfed, in this suction chamber 56 region, by an uptake supply passage 66referred to as a “throat supply passage.”

Fluid from the sump 64 is drawn into the suction chamber region andadducted towards the nozzle discharge flow stream when present, drawninto the throat inlet transition region, and then into the throat itselfwhere the two flows combine and momentums are averaged as ischaracteristic of jet pump operation. The jet pump throat passage 60 isin fluid communication with the inlet passage 68 to the positivedisplacement oil pump 70, so as to apply fluid pressure to this positivedisplacement pump's inlet passage 68 when the jet pump nozzle opens anddelivers pressurized oil at high velocity to the jet pump throat 60. Thepressurization of the positive displacement pump's inlet 68 providesadvantages in driving energy savings via so-called “hydraulicunloading,” i.e. the reduction of the pressure differential between thepositive displacement pump's inlet 68 and discharge passages 72.Additionally, further advantages are gained in cavitation deterrence,i.e. increase in the positive displacement pump's pre-cavitationoperating speed, via the enhanced pump filling that the inlet passage'selevated fluid pressure motivates. At operating conditions such as idlespeed, and especially with hot oil, when the system pressure is belowthe threshold required to open the JPV, the positive displacement pump70 draws its inlet flow from the sump 64, through the jet pump's throatsupply passage 66 and the throat inlet transition region 62, and thenthe throat passage 60 itself, without the jet pump valve injecting fluidand thus providing pressure increase.

The positive displacement pump's discharge passage 72 is in captivefluid communication with both a consumptive load 74 and the JPV's nozzlesupply passage 76. This allows a recirculation circuit to be formed fromthe pump's discharge 72, through the JPV nozzle supply passage 76,nozzle supply chamber 32 and nozzle 38 and throat 60, and then back tothe pump's inlet passage 68. This fluid circuit feeds unused pump outputflow volumes forcibly back to the pump's inlet 68 under pressure. Thefluid circuit thus efficiently “recycles” much of the pressure energy ofthe unused flow volumes, in terms of the hydraulic work required of thepump. The exemplary embodiment includes an appropriately proportioneddiffuser 78 downstream of the JPV throat, for the recovery of velocitypressure to the increase of static pressure, between the throat and thepump inlet. However, an abbreviated diffuser, or no diffuser, are to beunderstood as included in the scope of the claimed invention.

The spatial requirements for packaging flow-efficient configurations ofthe JPV's nozzle supply chamber are preferably minimized, along withside-loading of the JPV's sealingly mobile interface, by providing anecked down portion 58 of the nozzle sealing member 30 between its seatportion 34 and its sealingly mobile or body portion 40. In thisarrangement the nozzle supply flow area in the nozzle supply chamber 32is locally increased, to locally reduce flow velocity, and thereby alsothe area exposed to the incoming nozzle supply flow velocity is reduced.These area and flow velocity differences result in reduced side-loadingon the nozzle sealing member 30 due to flow impingement, andconsequently wear may thereby be reduced.

While these embodiments offer efficiency advantages by virtue ofadjustable nozzle jet pump efficiency benefits and the elimination ofpressure losses across a separate flow control valve, some applicationconditions will require measures to avoid throat flow restriction atpre-boost operating conditions. In the case of JPV applications thatspecify relatively high system pressure before “cracking” or beginningof recirculation flow (hereafter “high JPV cracking pressure systems”),the jet pump's throat area may need to be larger than optimal for boostefficiency in order to pass the entire inlet flow volume underatmospheric pressure motivation alone prior to the onset of nozzledischarge.

This throat size based efficiency limitation renders current art fixednozzle area single pump systems highly ineffective because of theoversized jet pump throats necessary to avoid choking their respectivepositive displacement pumps under some operating conditions.Additionally, throat size based efficiency limitation further renderscurrent art fixed nozzle area single pump systems highly ineffectivebecause of the appreciable recirculation flow volumes needed to achievenozzle discharge velocity dependent benefit from a fixed nozzle area jetpump.

In the case of high JPV cracking pressure systems, maximal systemefficiency over broad ranges of operating conditions may be achieved, bymeans whereby the jet pump's throat can be allowed to pass less than theentirety of system flow volume. This permits the throat to be sized forefficiency rather than in light of pre-boost flow velocity limitations.Two alternate embodiments provide a means of circumventing this “throatrestriction at pre-boost operating conditions” issue, and therebyenabling optimal JPV throat sizing. A first embodiment provides aparallel combination of the single positive displacement pump with JPVrecirculation circuit arrangement as discussed above with a supplementalpositive displacement pump, whose supply passage is separate andindependent of the JPV's throat area. A second embodiment provides anintroduction of additional inlet supply flow capacity downstream of theJPV's throat 60, between the jet pump's throat and the positivedisplacement pump's inlet 68, hereafter the “throat-to-pump inletpassage,” through at least one one-way check valve to provide the highflow capacity and low pressure drop characteristics needed tosufficiently minimize inlet vacuum and thus avoid cavitation.

In case of the first embodiment including a supplemental positivedisplacement pump, and referring now to the cavitation-deterringenergy-efficient fluid pump system 12 as illustrated in FIG. 3, the flowvolume from the sump 64 through supplemental pump inlet passage 82 tosupplemental pump 80, being discharged to load 74 through supplementalpump discharge passage 84 acts to reduce the operating speeds at whichunused oil becomes available to “power” the JPV, thus lowering thecritical speed for which the jet pump throat passage 60 must be sized,an efficiency advantage over the larger-than-optimal throat sizes ofprior art single pump systems. In this exemplary dual pump embodiment,the JPV may also incorporate an integral pressure relief or “bypass”port 86, which opens before the nozzle sealing member 30 has reached itsfully open second position. This allows an additional flow route for thesupplemental pump's flow volumes. This additional flow route may beadvantageous when operating at cold or “deadhead” flow restrictionconditions, or to avoid issues such as overpressurizing seals, that ofan oil filter for example. In the exemplary embodiment, this integratedbypass port 86 is formed by at least one opening or port in the wall ofa cylindrical valve bore 88 which maintains concentric location betweenthe circular cross-section nozzle sealing member's tapered sealingportion's sealing area 34, and its conical seat region 38 in the nozzleportion of the supply chamber 32. The bypass port 86 is positioned sothat it is only opened at the high pressure end of the nozzle sealingmember's 30 travel range. It should be appreciated that sealing portion34 and seat region 38 are described for exemplary purposes as having aparticular conical shape, however, other shape types, such as a concave,convex or spherical surface for example, could be used without deviatingfrom the intended scope of the claimed invention.

FIG. 4 schematically illustrates the cavitation-deterringenergy-efficient fluid pump system 12 illustrated in FIG. 3 with nozzlesealing member 30 at a bypass threshold position where furtherdisplacement from the first closed position towards the second openposition would enable fluid to escape through bypass port (74) andreturn either to the reservoir 64 or, alternatively, to the throatsupply passage 66.

FIG. 5 schematically illustrates the system 12 with nozzle sealingmember 30 in the second fully open position whereby bypass flow inbypass port 74 is enabled. The need for such pressure relieffunctionality in a given system is not certain because the unusedportion of the supplemental pump's flow volume may be able to escapethrough the JPV's nozzle, thus creating backflow out its throat supplypassage without exceeding engineering design limitations on systempressure.

Another embodiment for avoiding having the entirety of system supplyflow volume to pass through the JPV throat 60 in high JPV crackingpressure systems is illustrated in FIGS. 6-9. These embodiments have oneor more one-way (or check) valve(s) that may be used to providesupplemental (i.e. in addition to that which passes through the JPV'sthroat) intake flow to the positive displacement pump 70 if needed priorto pressurization of the throat-to-pump inlet passage. Afterpressurization of the positive displacement pump's inlet 68 passage byjet pump action commences, the one-way valve automatically closes tomaintain the pressurization, for “hydraulic unloading” energy savingsand cavitation speed increase.

FIG. 6 schematically illustrates a cavitation-deterring energy-efficientfluid pump system 14 which enables optimal throat sizing in a high JPVcracking pressure single pump system, namely the addition of one or moreone-way check valve inlet bypass passage(s), such as a ball-type checkvalve 90 for example, having inlet 96 that draws from the sump 64, andoutlet 98 that discharges to the throat-to-pump inlet passage 78 forintroduction of supply flow downstream of the JPV's throat 60. In thisfigure the system pressure has not yet opened the JPV, yet the pump'sinlet flow rate is such that without flow through the check valve 90,the flow rate through an optimally-sized jet pump's throat 60 might behigh enough to create substantial enough pressure drop across the throat60 as to cause premature cavitation in the pump 70. The ball 92 is shownin an elevated or open position above its valve seat 94 to provide lowresistance inlet flow to bypass the jet pump's throat passage 60, thusreducing the vacuum magnitude of the positive displacement pump's inletpassage 68 and thus avoiding premature pump cavitation at times prior tothe opening of the JPV.

FIG. 7 illustrates the same system with the ball 92 in a seated orclosed position, to resist loss of inlet boost pressure after JPVopening. Such ball-type check valves are available both with and withoutspring assist, the latter utilizing gravity to seat the ball asillustrated in FIG. 7. While normally offering more than adequatesealing performance, the employment of the customary solid balls in thisvalve type may not be well suited to highly vibratory applications suchas balance shaft modules due to the appreciable inertia forcesassociated with the mass of a solid ball when confronted by aggressivevibration. The location and configuration of the check-valved supplypassage's union with the positive displacement pump's throat-to-pumpinlet passage are arranged to minimize flow resistance whilerepresenting minimal interruption of diffuser functionality, such asutilization of Coanda effect shielded merging for example.

FIG. 8 illustrates the cavitation-deterring energy-efficient fluid pumpsystem 16 with a second alternate embodiment one-way check valve 100 inthe throat-bypassing supply passage 96, utilizing a low cost, low mass,and vibration resistant type of valve having a cup-shaped valve member102 including a substantially cup-shaped cross section. The cup shapedvalve member 102 has sides that slidingly engage a cup piloting springseat member 104 for wear resistant locating of the bottom area of thecup-shaped valve member 102. This provides for one-way sealing of asubstantially flat perimeter sealing surface 106 of the inlet bypasspassage 96. An optional cup-shaped valve member urging member or spring108 may aid gravity in urging the cup-shaped valve member 102 gentlytowards closure or sealing without greatly resisting bypass flow, whenneeded by certain applications. The proportions and spring rate of thisvalve 100 configuration can be tailored to provide very high flowcapacity at very low pressure drop. The cup-shaped valve member's 102sides may be circumferentially continuous or interrupted withoutdeparting from their radial positioning functionality in interactionwith the cup piloting spring seat member 104.

FIG. 9 illustrates the cavitation-deterring energy-efficient fluid pumpsystem 18 with a third alternate embodiment check valved inlet bypasshaving a so-called reed valve assembly check valve 110 positioned in thethroat-bypassing supply passage 96. This kind of multiple reed assembly110 is used in the intake ports of high performance two-stroke cycleengines and is capable of high flow capacity concurrent with relativelylow pressure drop. In one embodiment, reed valves 112 are sealinglymounted to a sealing reed frame member 114 that may also include reedtravel stops 116. The stops 116 provide motion control for the reedvalves 112, including the extent of their opening.

In some applications the predetermined threshold of pilot pressureneeded to open the JPV is allowed to be relatively low. In theseapplications, the throat flow volume prior to commencement of inletpressurization is also commensurately low. Therefore, the throat chokingissue and the need for its avoidance, may be irrelevant. Energy savingsare maximized in this case because after fully meeting an engine's hotidle flow requirements, only gradual increase in engine system pressurewith RPM is needed to overcome the increased centripetal forces actingon the oil in crankshaft oil passages. Any more than this gradualincrease is typically unnecessary for basic engine system performance.Therefore any incremental increase in pressure, pump hydraulic loadingand driving torque, over that which is needed to assure this basicsystem performance, represents wasted energy except where justified byconsumptive load devices that can more than make up for the drivingtorque increase by their contributions to engine performance.

Referring now to FIG. 10, an alternate cavitation-deterringenergy-efficient fluid pump system 20 is illustrated. In cases where thepressure drop across an oil filter and/or other consumptive load flowresistance is considered to have a larger than desired deviation betweenthe system delivery pressure as managed by the JPV, and the systempressure downstream of this resistance, the introduction of acavitation-deterring energy-efficient fluid pump system 20 with a nozzlesupply chamber sealing partition 118 is provided. This nozzle supplychamber sealing partition 118 allows sealing mobility of the cylindricalnozzle sealing member support 120 that is arranged between the seat 34of nozzle sealing member 30 and its body portion 40. The partition 118separates the sealingly mobile pressure reaction face area 42 of thenozzle sealing member 30 from the nozzle supply chamber 32. This allowsthe exposure of face 42 to a pilot pressure chamber 122. The pilotpressure chamber 122 provides exposure of the face 42 to the downstreamof resistance pilot pressure 124 rather than the fluid pressure from thedischarge passage 72. The downstream of resistance pilot pressure 124may be represented by an engine's oil gallery downstream of its filtersystem flow resistance for example. The use of the pilot pressurechamber 122 to actuate the nozzle sealing member 30 may be referred toas “remote pilot” control.

The cavitation-deterring energy-efficient fluid pump system isadvantageous when integrated into engine applications such asLanchester-type balance shaft modules where pump driving torques offercost-effective drive system noise control synergies, and yet wherepackaging space constraints prohibit the use of more complexvariable-displacement pump configurations. The embodiments disclosedherein, such as the positive displacement pump 70, the diffuser 66, andthe JPV, form a fluid circuit “chain.” This chain provides considerablepackaging flexibility in comparison with the substantially more complexvariable-displacement pump configurations, which require mechanicalproximity of all key elements.

At least one embodiment thus combines the cavitation-deterringenergy-efficient fluid pump system with at least one engine balancingshaft to form a balance shaft/oil pump apparatus (FIG. 19) for controlof gear noise emissions at minimum cost. Such balance shaft/oil pumpmodules are typically very highly constrained, in terms of availablepackaging space, because they are usually housed below the engine'scrankshaft, and therefore compete for available space with the engine'soil volume in the oil pan or wet sump, the oil level needing to staybelow the level of the spinning crankshaft and its connecting rods inorder to avoid needless oil aeration, oil heating, and powerconsumption. The spatial requirements for packaging flow-efficientconfigurations of a jet pump's typically largest diameter feature,namely its suction chamber, are a function of the advantages of smoothacceleration of the radially inward adduction flow approaching thethroat 60. This is conventionally significant, diameter-wise, in orderto establish the substantially axisymmetric adduction flow pattern formost efficient energy transfer between nozzle discharge flow and suctionchamber flow as they enter, past the throat inlet transition region,into the throat passage itself.

FIG. 10 illustrates an embodiment for minimizing the diameter of thesuction chamber in order to facilitate compact packaging. In thisembodiment, the throat supply passage 66 is located adjacent to anecked-down region 126 behind (i.e. remote from the suction chamber) athroat entry horn. The throat passage 60 includes a throat inlettransition region 62 such that substantially uniform axial flow cansupply the perimeter of the horn. The flow in this region 62 issubstantially free from “crosswind” effects from throat supply passage66 flow velocity. The necked down region circumscribing the throatpassage 60 lowers the velocity of the flow from the throat supplypassage 66. This allows the throat supply passage 66 to be a lowrestriction “elbow” that aligns the flow from the throat supply passage66 towards the suction chamber 56 into being substantially coaxial withthe throat passage 60.

In this embodiment, the substantially uniform gap around the bell of thethroat entry horn acts to produce substantially uniform flow velocityall around its periphery. This is advantageous in providing the desiredaxisymmetric flow pattern approaching the throat supply passage 66. Evenif the throat supply passage 66 is not entirely behind the throat entryhorn 62, such a necked down region can be helpful towards reducingcrosswind asymmetry of throat inlet transition region flow by increasingflow area without a corresponding increase in suction chamber diameter.In adverse packaging space conditions where fully axisymmetric suctionchamber designs are impractical, such flow area improvements as neckingbehind a throat entry horn 62 can be of particular value in a compromisesolution optimized by numerical methods, such as computational fluiddynamics methods for example. The embodiment of FIG. 10 further includesa vented-to-atmospheric damping reservoir 52 in fluid communication withthe nozzle sealing member 30 motion control means of damping orifice 48.

FIG. 11 illustrates the cavitation-deterring energy-efficient fluid pumpsystem 20 with the addition of an optional pilot pressure chamber seal128 that may be utilized to minimize leakage between the cylindricalnozzle sealing member support 120 of the nozzle sealing member 30 andthe nozzle supply sealing partition 118. Such a seal, if desired, may beoriented to withstand the always-higher pressure of the nozzle supplychamber 32.

In some applications, electronic or other logic based automated controlof system pressure may be desired in order to increase system deliveryflow rates under certain operating conditions, such as the opening of apiston cooling jet manifold valve for example. The nozzle-closing forceof the resilient urging member 44 may be supplied, or else supplemented,by a control apparatus such as an electronic or electromechanicalactuation device for example. FIG. 12 illustrates a cavitation-deterringenergy-efficient fluid pump system 22 having such an electronic controlmeans 130 as supplementation to a resilient urging member 44. It shouldbe appreciated that the electronic control means 130 may be coupled toone or more sensors (not shown) that provide feedback signals indicatingoperating conditions such as pressure of the fluid either within thecavitation-deterring energy-efficient fluid pump system 22 or theconsumptive load for example. The electronic control means 130 isresponsive to these signals in actuating the nozzle sealing member 30.The electronic control means 130 may be further responsive to pressureon the face 42 and activate based on the amount of pressure in supplychamber 32. Also shown is the necked down portion 58 of the nozzlesealing member 30 between the seat portion 34 and the body portion 40 asdiscussed above. It should be appreciated that such a control device 130maybe used alone as the urging member. Typically electromagneticsolenoids are used for electronic actuation, however, their continualpower draw when exerting a control force is counterproductive to netenergy efficiency. Therefore, the use of alternative devices may bedesirable.

FIG. 13 illustrates a cavitation-deterring energy-efficient fluid pumpsystem 24 with the optional combination of both remote pilot pressure124 and electronic pressure control means 130, whereby system pressureis passively managed to maintain threshold downstream-of-resistancetargets, and may additionally be actively managed for specific purposeswhen desired.

FIG. 14 illustrates an alternate embodiment cavitation-deterringenergy—efficient fluid pump system 25 having actuation of the nozzlesealing member 30 by the electronic control means 130 without theassistance of spring 44. In this embodiment, the electronic controlmeans 130 includes a plunger 132. The plunger 132 is coupled to the bodyportion 40 and arranged to be moved linearly along an axis parallel tothe axis of the nozzle sealing member 30. This movement causes thesealing seat 34 of member 30 to move into and out of contact with nozzleseat 38.

[In applications where the sealingly mobile functionality of the nozzlesealing member 30 with respect to the nozzle supply chamber 32 must benearly leak-free, a piston and cylinder type apparatus may be fittedwith at least one o-ring or other sealing device. In other applicationswhere the sealingly mobile functionality of the nozzle sealing member 30and chamber 32 must be completely leak-free, a sealing mobility portion36 comprising a diaphragm-type apparatus, including bellows-typediaphragm may also be used. FIG. 15 illustrates such a sealingly mobilediaphragm type cavitation-deterring energy-efficient fluid pump system26. In this embodiment, a sealing tip 136 is coupled to the body portion142 of the nozzle sealing member 30. The sealing tip 136 includes a seatarea 138 that contacts the nozzle seat 38 when the sealing member 30 isin the first position. A diaphragm member 140 is also coupled to thebody portion 142. The diaphragm member 140 provides the reaction surfaceupon which the fluid pressure from discharge passage 72 acts. The spring44 biases the sealing tip 136 into contact with the nozzle seat 38.

It should be appreciated that other types and constructions of sealingmobility portion 36's diaphragm type cavitation-deterringenergy-efficient fluid pump system 26 may be used. For example, thediaphragm member 140 may be bonded to the sealing tip 136, or a formedprotrusion of the diaphragm may be press fit onto the sealing tip 136.This would allow the elimination of the spring guide. Further, thediaphragm member 140 may be used itself as the urging member allowingthe elimination of the separate spring.

FIG. 16 illustrates a cavitation-deterring energy-efficient fluid pumpsystem 28 wherein leak-free sealing mobility of the JPV's nozzle sealingmember with respect to the nozzle supply cavity is provided by a bellowstype diaphragm. In this embodiment, the spring 44 acts upon a bodyportion 142 as described herein above. The body portion 142 is coupledto a sealing body 144. Sealing body 144 includes a seat region 146 thatcontacts the nozzle seat 38 when the sealing member 30 is in the firstposition. The sealing body 144 is generally cone shaped and includes apilot flange portion 148 that is axially mobile within a pilot diameter150. A bellows member 152 is coupled to the body portion 142. Thebellows member's 152 minor diameter represents the outside of thefunctional area of pressure reaction face 42, so this diameter is sizedin conjunction with mating component properties such as nozzle seatdiameter, urging member static force and rate of force change (e.g.spring rate), in light of desired system fluid pressure range. A dampingorifice 154 is arranged in the spring pocket 54 opposite the bodyportion 142. During operation, the bellows member 152 compresses andexpands axially to enable nozzle sealing member 30 motion within nozzlesupply chamber 32. During this motion, the large pilot flange 148 isable to “leak” oil back and forth to the diaphragm OD region.

FIG. 17 illustrates a cavitation-deterring energy-efficient fluid pumpsystem 29 having an electronic control means 156 similar to controlmeans 130 discussed above in reference to FIG. 12. Control means 156acts on the spring 44 instead of acting directly on the nozzle sealingmember 30. The control means 156 includes an actuator, such as asolenoid or a stepper motor for example, that actuates a spring support158. The spring support 158 has a spring support face 160 that may bemoved linearly by the control means 156 from a first or initial positionto a second position in response to a switching event. The movement ofthe spring support 158 changes the amount of compression of spring 44,and thus the magnitude of the force provided by spring 44. In theexemplary embodiment, the spring support 158 may be held at the secondposition without further energy expenditure. The spring support 158 mayremain in this position until another switching event, such as theclosing of a piston cooling jet manifold valve for example, causes thecontrol means 156 to restores the spring support 158 to the initialposition. This embodiment provides the advantage of using a normallypassive type electronic control 156 such as a stepping motor instead ofan electronic control such as a solenoid that continually draws power inorder to exert an axial force. Such a normally passive electroniccontrol 156 may be activated when a significant change to enginepermeability occurs, such as the opening of a piston cooling jetmanifold valve for example. This type of activation may result in adesired new degree of spring 44 preload that may be used to maintainsystem pressure under such a higher permeability condition. This preloadof the spring 44 may then be maintained without need for the control 156to actively respond to system pressure changes. This use of a normallypassive type electronic control provides the advantage of increasedenergy savings in comparison with an electronic control that requirescontinual electrical power to exert a force.

FIG. 18 illustrates empirical test data comparing the pressure curves ofa conventional PRV-regulated single positive displacement pump and aFIG. 1 cavitation-deterring energy-efficient fluid pump system(“C-dE-EFPS”) 10. The test setup between the two tests differed only inrespective hydraulics, as needed to achieve a hypothetical high-speedpressure requirement. The PRV testing results are defined by dashed-line158, while that of the exemplary embodiment fluid pump system 10 isdefined by line 160. The PRV system recirculates its bypass oil directlyback to the pump's inlet, merging with sump uptake oil in a favorabledirection within 1 cm of the pump, in a routing commonly termed“supercharging.” As can be seen from curve 158, the PRV-regulated systempressure begins to falter at point 166 due to cavitation beginningaround 5200 rpm, while the inlet pressurization benefit of the C-dE-EFPS10 enables its outlet pressure to rise steadily to nearly 8000 rpm.

FIG. 19 compares empirical drive system power consumption curves for theFIG. 17 test conditions. The PRV test results are defined by dashed-line168, while those of the fluid pump system 10 is defined by line 170. Theapproximately 19% average difference in drive system power consumptionover the most frequently-used speed range understates the actual pumppower consumption difference, because the drive system friction losses(from spindle bearings, spindle seals, chain, sprockets, chain tensionerand chain guide) are also included in these curves.

The cavitation-deterring energy-efficient fluid pump system may be usedin a number of applications. FIG. 20 illustrates one such applicationwhere the cavitation-deterring energy-efficient pump system 172,including a positive displacement pump 174 arranged with an adjustablenozzle jet pump valve 178 and reservoir 180 as described embodimentsillustrated in FIGS. 1-16, is coupled to a balance shaft modularassembly 184. The positive displacement pump 174 includes a dischargepassage 182 that transfers fluid, such as a petroleum-based lubricant,to the engine 186 through a filter 194. The positive displacement pump174 is drivingly connected to the engine 186 that provides the energyfor operation of the positive displacement pump 174. In the connection176 the positive displacement pump 174 is mechanically connected.

The modular assembly 184 delivers the fluid to an engine 186, such as aninternal combustion engine for example. In the exemplary embodiment, theengine 186 includes one or more pistons 188, each with a connecting rodassembly 190. The delivered fluid is cleaned by filter 194 and then usedwithin both engine 186 and modular assembly 184 before being returned toreservoir 180 via at least one return passage 192.

The embodiments described herein provide a cavitation-deterringenergy-efficient fluid pump system that provides advantages in extendingthe working speed range of a positive displacement pump. Thecavitation-deterring energy-efficient fluid pump system further providesadvantages in reducing the driving power consumption of a positivedisplacement pump over its typical operating speed range. Additionaladvantages are made in minimizing the packaging space claim of apositive displacement pump system having jet pump-assistedrecirculation, and to enable its design flexibility with regards toapplication packaging constraints. Additional advantages are provided tominimize manufacturing costs. The cavitation-deterring energy-efficientfluid pump system also provides advantages in enabling control by meansremote from the positive displacement pump's output pressure where sodesired.

The embodiments described herein provide further improvements in thatthe aforementioned differential control means of prior art valvemechanisms are larger, and thus disadvantaged in terms of packageabilityand cost, for any given combination of urging force and nozzle flowcapacity. In comparison, the embodiments provided herein include furtheradvantages because the valve motion motivating pressure area of priorart mechanisms is reduced by both the nozzle seat area and that of thesmaller of two piston diameters. Further, the fluid pressure acting onthis reduced pressure area is only the net difference between the outputpressure and the input pressure, with the input pressure typically beingpositive. In comparison, the valve motion motivating pressure area ofthe embodiments provided herein is reduced by only the nozzle seat area,and the fluid pressure acting on this pressure area is not influenced byinlet pressure.

While the present invention has been described with reference topreferred embodiments, obviously other embodiments, modifications, andalternations could be envisioned by one skilled in the art upon readingthe present disclosure. The present invention is intended to cover theseother embodiments, modifications, and alterations that fall within thescope of the invention upon reading and understanding this specificationwith its appended claims.

1. A pump system comprising: a first positive displacement pump havingan inlet passage and a discharge passage; and an adjustable nozzle jetpump valve having: a supply chamber fluidly coupled to said dischargepassage, said supply chamber further having a port with a seat surface;a movable valve member having a sealing surface in sealing contact withsaid seat surface when in a first position, and a body portion, saidbody portion further having a first face sealingly positioned withinsaid supply chamber, and an opposing second face, said first face havinga first surface area; an urging member coupled to said second face; asuction chamber fluidly coupled to said port; a throat passage fluidlycoupled to said suction chamber and said inlet passage wherein saidport, said suction chamber and said throat passage are arranged in acontinuous serial fluid connection to said inlet passage.
 2. The pumpsystem of claim 1 wherein said adjustable nozzle jet pump valve includesan orifice fluidly coupled to said second face.
 3. The pump system ofclaim 2 wherein said orifice is vented to atmospheric pressure.
 4. Thepump system of claim 2 wherein said venting to atmospheric pressure isby means of fluid coupling with an oil reservoir exposed to atmosphericpressure.
 5. The pump system of claim 1 wherein said urging member is aspring arranged to bias said movable valve member sealing surfaceagainst said seat.
 6. The pump system of claim 1 wherein said urgingmember is an electromechanical actuator.
 7. The pump system of claim 1further comprising: an uptake passage fluidly coupled to said suctionchamber and to a fluid reservoir; and, a one-way check valve fluidlycoupled between a fluid reservoir and said inlet passage.
 8. The pumpsystem of claim 1 wherein said throat passage comprises an entry bellfor smoothing the acceleration of flows entering said throat passage,said entry bell having outside diameter larger than an outside diametercircumscribing said throat passage.
 9. The pump system of claim 1wherein said adjustable nozzle jet pump valve includes a diaphragmmember coupled to said body portion.
 10. The pump system of claim 1wherein said adjustable nozzle jet pump valve includes a bellows membercoupled to said body portion.
 11. The pump system of claim 1 furthercomprising: a fluid reservoir fluidly coupled to said suction chamber;and, a second positive displacement pump fluidly coupled between saidfluid reservoir and said discharge passage.
 12. The pump system of claim1 wherein said adjustable nozzle jet pump valve further comprises apilot chamber positioned between said body member and said supplychamber.
 13. A pump system for a variable consumptive load, said systemcomprising: a first positive displacement pump, said pump having aninlet passage and a discharge passage, wherein said discharge passage isarranged to couple with said variable consumptive load; a jet pump valvehaving a variable nozzle opening area fluidly coupled between saiddischarge passage and said inlet passage, said jet pump valve includingmeans for changing the area of said variable nozzle opening in directresponse to changes in fluid pressure in said discharge passage, saidjet pump valve further including an urging member arranged to bias amember to close said variable nozzle opening; said jet pump valvefurther having a suction chamber adjacent said variable nozzle openingand arranged to receive fluid from said variable nozzle opening and froma fluid reservoir; said jet pump valve further having a throat passagecoupled to said suction chamber, said throat passage being fluidlycoupled to receive fluid from said reservoir and from said variablevalve opening, and to transfer said received fluid to said inletpassage.
 14. The pump system of claim 13 wherein: said means forchanging the size of said variable nozzle opening comprises: a supplychamber in direct fluid connection to said discharge line; and, a valvebody movable between a first position and a second position, said valvebody having a sealing member with a first cross sectional area and afirst face with a second surface, where in said second surface's area isgreater than said first cross sectional area, and wherein said sealingmember is in contact with and closes said variable nozzle opening whensaid valve body is in said first position.
 15. The pump system of claim14 further comprising a damping chamber, wherein a portion of said valvebody forms a portion of one side of said damping chamber.
 16. The pumpsystem of claim 15 further comprising a damping orifice fluidly coupledto said damping chamber.
 17. The pump system of claim 16 wherein saiddamping orifice is vented to atmospheric pressure by means of fluidcoupling with an oil reservoir exposed to atmospheric pressure.
 18. Thepump system of claim 13 further comprising: a fluid reservoir fluidlycoupled to said first positive displacement pump; and, a second positivedisplacement pump fluidly coupled between to said fluid reservoir andsaid discharge passage.
 19. The pump system of claim 18 furthercomprising a bypass passage fluidly coupled to said supply chamber whensaid valve body is in said second position.
 20. The pump system of claim13 further comprising a one way check valve fluidly coupled between saidreservoir and said inlet passage adjacent one end of said throat passageopposite said inlet transition region.
 21. The pump system of claim 20wherein said valve is a ball and seat type valve or a reed type valve.22. The pump system of claim 20 wherein said valve includes a memberhaving a substantially cup-shaped cross-section, and a seat, said cupshape having sides which slidingly engage a pilot member for locating ofa face area of said cup-shaped member in sealable proximity to saidseat.
 23. The pump system of claim 13 wherein said urging member is acompression spring.
 24. The pump system of claim 13 wherein said urgingmember is an electromechanical actuator.
 25. The pump system of claim 14further comprising a pilot pressure chamber adjacent said first face,wherein said pilot pressure chamber having a partition wall thatinhibits flow from said supply chamber to said pilot pressure chamber.26. The pump system of claim 25 further comprising a seal arrangedbetween said supply chamber and said pilot pressure chamber.
 27. Thepump system of claim 13 wherein said throat passage further includes aninlet transition region coupled to said suction chamber.
 28. The pumpsystem of claim 13 wherein said means for changing the area of saidvariable nozzle opening is in direct response to changes in fluidpressure in said consumptive load.
 29. The pump system of claim 13further comprising an actuator movable between a first position and asecond position, said actuator being coupled to said urging member,wherein said urging member provides a first force when said actuator isin said first position and a second force when said actuator is in saidsecond position.
 30. A method of operating a pump system comprising:pressurizing a fluid with a positive displacement pump; discharging saidfluid into a discharge passage; flowing a portion of said fluid fromsaid discharge passage directly into a valve supply chamber; applyingpressure to a valve body face; moving said valve body; opening a port insaid valve supply chamber; ejecting said fluid into a suction chamber;and, increasing the fluid pressure at an inlet to said displacement pumpby injecting said fluid across a suction chamber into a throat passagewhich also receives fluid from a reservoir by means of said suctionchamber.
 31. The method of claim 30 further comprising the step ofvarying the opening area of said port in direct response to changes inpressure of said fluid in said outlet passage.
 32. The method of claim31 further comprising the steps of: adducting fluid in said suctionchamber towards said injected fluid; flowing said adducted fluid andsaid injected fluid into a throat passage; flowing said adducted andinjected fluids to said displacement pump inlet.
 33. The method of claim30 further comprising the step of biasing said valve body towards saidport.
 34. The method of claim 33 wherein said step of moving said valvebody occurs if the pressure in said discharge passage increases beyond afirst threshold.
 35. The method of claim 34 further comprising the stepof opening a one-way valve fluidly coupled to said inlet if pressure atsaid inlet is less than a second threshold.
 36. The method of claim 30further comprising the step of powering said positive displacement pumpby driving connectivity with a balance shaft for an internal combustionengine having at least one piston and connecting rod assembly.
 37. Themethod of claim 36 further comprising the step of transferring saidfluid to said internal combustion engine.
 38. The method of claim 29further comprising the steps of: applying a force with an urging memberto said valve body; and, changing the magnitude of said force inresponse to a switching event.
 39. An internal combustion enginecomprising: a balance shaft assembly; a first positive displacementpump, said pump having an inlet passage and a discharge passage, whereinsaid discharge passage is arranged to fluidly couple with said balanceshaft assembly; a jet pump valve having a variable nozzle opening areafluidly coupled between said discharge passage and said inlet passage,said jet pump valve including means for changing the area of saidvariable nozzle opening in direct response to changes in fluid pressurein said discharge passage, said jet pump valve further including anurging member arranged to bias a member to close said variable nozzleopening; said jet pump valve further having a suction chamber adjacentsaid variable nozzle opening and arranged to receive fluid from saidvariable nozzle opening and a fluid reservoir; and, said jet pump valvefurther having a throat passage coupled to said suction chamber, saidthroat passage being fluidly coupled to receive fluid from saidreservoir and said variable valve opening and transfer said receivedfluid to said inlet passage.
 40. The internal combustion engine of claim39 wherein said means for changing the area of said variable nozzleopening is in direct response to changes in fluid pressure in saidinternal combustion engine.
 41. The internal combustion engine of claim39 further comprising an actuator movable between a first position and asecond position, said actuator being operably coupled to said urgingmember wherein said urging member provides a first force when saidactuator is in said first position and a second force when said actuatoris in said second position.